1. Field of Invention
The present invention relates to a wireless network device, and more particularly, to a wireless network device capable of automatically setting a parameter for signal transmission with a wireless device.
2. Related Art
Nowadays, a wireless network device adopts a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) technology for medium access control, and after sending data, acknowledges that the data transmission is successful according to an ACK frame received within a preset ACK timeout interval.
FIG. 1 is a schematic view of data collision of wireless network devices in the prior art. Referring to FIG. 1, a first network device 11 sends data to a second network device 12, and the second network device 12 returns an ACK frame to the first network device 11 after successfully receiving the data. If the first network device 11 receives the ACK frame within a preset time interval after the data is sent, it indicates that the data transmission is successful; on the contrary, if the first network device 11 does not receive the ACK frame within the preset time interval after the data is sent, it indicates that the data transmission is fail, and in this case, the first network device 11 retransmits the data after the preset time interval is timed out.
As shown in FIG. 1, a packet turnaround time T1 between the first network device 11 and the second network device 12 includes the following: (1) a packet transmission time from the first network device 11 to the second network device 12; (2) a working time T3 of the second network device 12, where the working time T3 includes a packet processing time, a short inter frame space (SIFS) and other necessary processing time required by the second network device 12 to transmit the ACK frame; and (3) an ACK transmission time from the second network device 12 to the first network device 11. It should be understood that the packet transmission time and the ACK transmission time are the same transmission time T2, and the packet turnaround time T1 is two times the transmission time T2 plus the working time T3 of the second network device 12, that is, T1=(2*T2)+T3. Therefore, an ACK timeout interval T4 is a sum of the packet turnaround time T1 and the working time T3. It can be known from the above that, if the first network device and the second network device are far away from each other, as the transmission time T2 increases, the packet turnaround time T1 may be larger than the ACK timeout interval T4, so that the sending network device misjudges that the previous data transmission fails, and sends the data again, resulting in false operation.
If the first network device 11 and the second network device 12 are installed outside to serve for bridging data packets sent by a wireless terminal apparatus, a distance between the two network devices 11 and 12 is generally far from each other. Due to above mentioned reasons, the distance between the two wireless network devices or ACK timeout intervals usually needs to be manually configured to the wireless network device separately by technicians. Therefore, the wireless network device could avoid leading false operations in various distances by the configured distance or ACK timeout interval.
However, such operations for configuring distance or ACK timeout interval are mostly completed manually, and the distance between the network devices needs to be measured in advance through various measurement methods. Also, the distance can be defined by adjusting and setting the ACK timeout interval in a try-error manner or setting a large ACK timeout interval. Therefore, it will lead a rather labor- and time-consuming.
Therefore, how to automatically and properly set a parameter value for an ACK timeout interval of a wireless network device is a problem to be considered by manufacturers nowadays.